This invention relates to scroll fluid apparatus, and, more particularly, to a scroll fluid compressor wherein an improved seal is provided between forward ends of the wraps and end plates of scroll members of the scroll fluid compressor.
A scroll type fluid compressor is disclosed, for example, in U.S. Pat. No. 3,884,599 which comprises an oribiting scroll member and a stationary scroll member. The orbiting scroll member comprises an end plate, and a wrap of the vortical form upstanding on the end plate and having an involute curve or a curve similar thereto, and the stationary scroll member comprises an end plate and a wrap similar in construction to those of the orbiting scroll member and is formed with an outlet port substantially in the center of the end plate, and an inlet port opening at the outer side of the end plate. The orbiting scroll member and the stationary scroll member are brought into contact with each other in such a manner that the wraps of the two members are meshing with each other while being maintained at their forward ends in intimate contact with the surfaces of the opposite end plates. The two scroll members arranged are housed in a housing having an inlet line and an outlet line connected thereto.
An Oldham's ring, which is a rotation-on-its-own-axis preventing member, for the orbiting scroll member is mounted between the orbiting scroll member and the stationary scroll member, and a crankshaft is in engagement with the orbiting scroll member to cause the latter to move in orbiting movement without rotating on its own axis. A fluid is compressed in sealed spaces defined between the two scroll members and the compressed fluid is discharged through the outlet port.
It has been usual practice to machine the side surfaces of the vortical wraps and the end plates of the scroll members of a scroll fluid compressor by a machine tool, such as a numerically controlled milling machine. However, the disadvantage of this method resides in the fact that difficulties are encountered in machining the portions of the end plates which constitute volleys between the wraps to achieve flatness thereof with a high degree of precision. The surface of the machined end plates is rather coarse, making it difficult to provide a satisfactory seal between the forward ends of the wraps and the end plates when the orbiting scroll member moves in orbiting movement in cooperation with the stationary scroll member. The coarse surface of the end plates causes a high friction loss and seizure of the forward ends of the wraps to occur.
More specifically, the method of working on the end plates that has been used has been unable to achieve satisfactory results in providing a smooth sliding surface because the surface obtained has had a coarseness of about 10s (according to Japanese Industrial Standards). Additionally, when the end plates are subjected to surface treatment to increase their hardness, the end plates have tended to suffer deformation and their flatness has been reduced.
To obviate the aforesaid problems, in, for example, U.S. Pat. No. 3,994,635, it has been proposed to prepare the end plate and the vortical wrap separately and work on them independently, and mount the wrap in a groove formed in the end plate after achieving a desired flatness in the surface of the end plate. In, for example, U.S. Pat. No. 3,986,799, scroll fluid compressor is proposed wherein the wrap is firmly secured to the end plate by bolts after being separately prepared and independently worked on.
When the separately prepared vortical wrap and the end plate are independently worked on, means for securing the wrap in the groove formed in the end plate become complex in construction and might cause a reduction in reliability. Bolting of the wrap to the end plate would suffer the disadvantages that the wrap itself might suffer deformation and the working steps would increase in number.
In, for example, Japanese Laid Open Application No. 35155/80, still another type of scroll fluid compressor is proposed wherein a resilient member is fitted on the bottom of the valley between the wraps of the scroll members having the end plates and the vortical wraps formed integrally. The resilient member comprises a rubber member and a plate spring formed of SK steel, bronze, etc., secured to the surface of the rubber plate. However, problems arise with regard to the resistance of rubber to a refrigerant and the difficulty with which a spring material may be secured to the rubber plate.